Cooked too long or not enough ?

I did these baby back ribs on Sunday, 2 hours in the smoker uncovered, 2 hours wrapped(apple juice) and 1 hour back on the racks (all @ 225). I grabbed the end w/tongs and had a semi bend with ribs. They seemed a bit tough, I did not spritz and am wondering if I cooked too long OR not enough to get the meat to break down a bit more ? Any help will be appreciated ,Thanks CM